Predictors for the Need of Surgery in Antenatally Detected Hydronephrosis: A Retrospective Multivariate Analysis

Background: Antenatal hydronephrosis (ANH) is observed in 1% to 2% of all pregnancies. Controversy exists over the ability of different diagnostic tests to define which patients will benefit from surgical intervention in ANH.

Objective: The objective of this study was to assess the ability of prenatal ultrasound and postnatal dynamic scintigraphy to predict an unfavorable outcome and the need for postnatal surgery in cases of ANH.

Methods: Retrospective single centre study involving 113 renal units at a neonatology department in Tunisia during a period of 9 years (2007-2015). Patients on conservative management were followed using a standard protocol and operated for pre-defined indications defining failure of conservative management. Patients who underwent surgery were compared with the non-operated group in terms of sex, side, baseline grade of hydronephrosis, maximum anterioposterior diameter on first postnatal ultrasound and differential renal function on first renal scan.

Results: Prenatal HN was made and confirmed in postnatal in 113 renal units (for a total of 84 patients). Of those, 11 patients (22.6%) required operative intervention during follow up. Median time of failor operative intervention was 18 months. The median follow up of non operated cases was 4 years.

Univariate analysis revealed that society of fetal urology (SFU) grade of hydronephrosis, anteroposterior diameter (APD), cortical thickness (CT), the presence of oligoamnios and pre-operative differential renal function (DRF) in postnatal dynamic scintigraphy had a significant association with surgery (P < 0.05). Multivariate analysis revealed oligoamnios, APD and pre-operative DRF as the only independent predictors for requiring surgery, while CT and initial SFU grade of hydronephrosis were not.

Conclusion: Oligoamnios, APD and DRF are the predictive factors for surgery. We stop short of recommending surgery only on the basis of APD. Instead we recommend that efforts be made to confirm our results.